THEY ARE GLUTTONS for punishment over at Channel 4. Last year, the station suffered huge embarrassment when a documentary called "Daddy's Girl" was revealed the day before transmission to be a hoax: the man purporting to be Victoria Greetham's doting father was really her boyfriend, Stuart Smith. But showing a plucky determination to retrieve something from the wreckage, last night's Cutting Edge (C4) went in search of Stuart and Victoria to find out what lay behind the scam.

The reasoning behind this masochistic exercise was unclear. From time to time, Riete Oord's film did raise the question of whether television blurred the distinction between fiction and reality. Stuart, tracked down to a West Yorkshire pub where he was living, tried to claim some legitimacy for his part in the hoax. "The events were real, they were real what happened on film, but they just weren't... hang on, were they real? Yeah, they were real. They WERE real... I'm confusing myself here because the documentary that they made was a real documentary. But there was just some lies involved in it." Later, Victoria made a similar point more tersely: "Nothing on TV's real, is it?"

You could see what they were getting at. In an an extract from an interview recorded shortly after the hoax was revealed, Angela Rippon accused them of lying and deception while sitting in a TV studio dressed up to look like somebody's sitting room. Peter Moore, the commissioning editor responsible for the original documentary, seemed to give a sidelong endorsement to Stuart and Victoria's muddled ontology, calling "Daddy's Girl" "a defining moment in the sort of post-modern world of television".

But this was allowing the scam a dignity it did not deserve. Watching Stuart perform for Oord's cameras and in the original documentary, it seemed clear that he took a simple, boyish pleasure in putting one over on the film-makers. Oord filmed him trying to blag his way on to another Channel 4 documentary about men with unusually large penises ("I am blessed," he told the programme researcher). Stuart was also operating as a damp-proofing consultant under the name "West Yorkshire Advisory Services"; Oord visited a dissatisfied customer who planned to take him to the small claims court, having previously expressed her anger by chanting a Buddhist mantra at him down the telephone.

In the end, Who's Been Framed? had some amusing moments, but drew no firm conclusions and took a long time about doing it. If Channel 4 had to use a sledgehammer, it could at least have made sure it cracked the nut.

By a perverse piece of scheduling, this came on immediately after Riddle of the Skies (C4), an annoyingly credulous three-parter on UFOs which offered eye-witness testimony and photographs as sound evidence for the presence of extra-terrestrial beings. The truth is that, given our current state of knowledge, the presence of ETs is so unlikely that almost nothing can count as hard evidence for it - fakery or delusion will always be a more likely explanation. It may be true that nothing is real on TV, but some things are still a lot less real than others.